Method of fabricating an EL display device, and apparatus for forming a thin film

ABSTRACT

A plurality of processing chambers are connected to a common chamber ( 103  in FIG.  1 ), and they comprehend a processing chamber for oxidation ( 107 ), a processing chamber for solution application ( 108 ), a processing chamber for baking ( 109 ), and processing chambers for vapor-phase film formation ( 110, 111 ). Owing to a thin-film forming apparatus of such construction, it is permitted to fabricate an EL (electroluminescence) element employing a high-molecular EL material, without touching the open air. Thus, an EL display device of high reliability can be fabricated.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a thin-film forming apparatus which isemployed for the fabrication of a display device having an EL(electroluminescence) element (hereinbelow, termed “EL display device”),and to a method of fabricating the EL display device as employs thethin-film forming apparatus.

2. Description of the Related Art

In recent years, researches have been vigorously made in EL displaydevices each of which has an EL element as a spontaneous emission typeelement. In particular, notice has been taken of an organic EL displaydevice which employs an organic material as an EL material. The organicEL display device is also called the “organic EL display (OELD)” or“organic light emitting diode (OLED)”.

Unlike a liquid crystal display device, the EL display device is ofspontaneous emission type and therefore has the merit of involving noproblem on a view angle. In other words, the EL display device is moresuitable than the liquid crystal display device as a display which isused outdoors, and its application in various forms has been proposed.

The EL element has a construction in which an EL layer is sandwiched inbetween a pair of electrodes, and in which this EL layer has amultilayer structure ordinarily. Typically mentioned is the multilayerstructure of “hole transporting layer/light emitting layer/electrontransporting layer” proposed by Tang et al., Eastman Kodak Company. Themultilayer structure exhibits a very high emission efficiency, and mostof the EL display devices being currently under research and developmentadopt this structure.

Herein, a predetermined voltage is applied to the EL layer of the abovestructure by the pair of electrodes, whereby light is emitted owing tothe recombination of carriers taking place in the light emitting layer.There are two sorts of schemes for the light emission; a scheme whereinthe EL layer is formed between two stripe-like electrodes disposedorthogonally to each other (simple matrix scheme), and a scheme whereinthe EL layer is formed between pixel electrodes connected to TFTs andarrayed in the shape of a matrix, and a counter electrode (active matrixscheme).

Meanwhile, the EL materials of the hole transporting layer, the lightemitting layer, etc. are broadly classified into two; a low molecularmaterial, and a high molecular material. While materials mainlyincluding Alq₃ have been known for a low-molecular light emitting layerfor a long time, a high-molecular (polymeric) light emitting layer hasbeen noticed especially in Europe in recent years. Typically mentionedare PPV (polyphenylene vinylene), PVK (polyvinyl carbazole),polycarbonate, etc.

The reasons why the high-molecular EL material is noticed are the pointsthat it can be formed into the layer by a simple method of forming athin film, such as spin coating process (also termed “solutionapplication process”), dipping process, printing process or ink jetprocess, and that it is higher in the thermal stability as compared withthe low molecular material.

Usually, the low-molecular EL material is formed into the layer byvacuum evaporation. That is, ordinarily the EL material is successivelystacked without breaking a vacuum in a vacuum evaporator. Besides, anelectrode of small work function is employed as the electrode acting asthe cathode of the EL element, and also this cathode is ordinarilyformed in succession to the EL material.

The EL material is extraordinarily liable to oxidize, and the oxidationis readily promoted even by the presence of a slight water content tillthe degradation of this EL material. In case of forming the EL element,therefore, the surface of the anode thereof being the lowermost layer isfirst preprocessed to eliminate moisture etc., whereupon the EL materialand the cathode are successively formed on the anode without breaking avacuum. On this occasion, the EL material and the cathode are sometimesdeposited on the selected parts of the anode by employing a shadow maskor the like, and all the processing steps are performed in an evacuatedprocessing chamber even in such a case.

This holds true also of the high-molecular EL material. Even in case ofthe spin coating process etc. which are not a thin-film formingexpedient in a vacuum, it is important for the suppression of thedegradation of the EL material that the EL material is prevented frombeing exposed in the atmospheric air which contains moisture.

SUMMARY OF THE INVENTION

The present invention has been made in order to fulfill the aboverequirements, and has for its object to provide a thin-film formingapparatus which is the most favorable for the fabrication of an ELdisplay device employing a high-molecular EL material.

Another object is to provide a method of fabricating an EL displaydevice of high reliability by utilizing such a thin-film formingapparatus.

The purport of the present invention consists in that an EL displaydevice is fabricated using a thin-film forming apparatus ofmulti-chamber system (also termed “cluster tool system”) or in-linesystem which integrally comprehends means for forming a thin film madeof a high-molecular EL material (hereinbelow, the thin film shall besometimes termed the “high-molecular EL layer”), and means for forming acathode.

While there are various methods of forming the film of thehigh-molecular EL material, the adoption of a spin coating process isfavorable. The spin coating process is an expedient wherein a solute tobecome the main component of the thin film is dissolved in a solvent,the resulting solution is applied by a spinner or the like, and thesolvent is subsequently volatilized by a baking process, thereby to formthe thin film.

In the present invention, the solution containing the high-molecular ELmaterial is applied by the spinner, and the solvent is volatilized byperforming a heat treatment at a temperature at which the high-molecularEL material is not crystallized (concretely, at a temperature which isnot higher than a glass transition temperature). As a result, thehigh-molecular EL layer is formed on a substrate. In other words, theformation of the high-molecular EL layer necessitates means for applyingthe solution containing the high-molecular EL material, and means forbaking after the application.

Besides, the high-molecular EL material is weak against oxygen likewiseto a low-molecular EL material, and an electrically conductive film tobe provided after the formation of the high-molecular EL layer shoulddesirably be formed so that this high-molecular EL layer may not beexposed to an environment containing moisture or oxygen. It canaccordingly be said that the means for forming the high-molecular ELlayer (in the present invention, means for executing the spin coatingprocess), and the means for forming the conductive film to serve as thecathode (or an anode), on the high-molecular EL layer (means forexecuting a vapor-phase film formation process such as vacuumevaporation or sputtering) should desirably be installed in theidentical thin-film forming apparatus.

The present invention achieves the above requirements by the thin-filmforming apparatus of multi-chamber system, and consists in technologyfor fabricating the EL display device of high reliability by adoptingsuch a thin-film forming apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view showing the construction of a thin-filmforming apparatus embodying the present invention;

FIG. 2 is a schematic plan view showing the construction of a thin-filmforming apparatus in another embodiment of the present invention;

FIG. 3 is a schematic plan view showing the construction of a thin-filmforming apparatus in still another embodiment of the present invention;

FIG. 4 is a schematic plan view showing the construction of a thin-filmforming apparatus in yet another embodiment of the present invention;

FIGS. 5(A) through 5(D) are sectional views showing a process forfabricating an active matrix type EL display device; and

FIGS. 6(A) through 6(E) are sectional views showing another process forfabricating an active matrix type EL display device.

PREFERRED EMBODIMENTS OF THE INVENTION Embodiment 1

An apparatus for forming a thin film in an embodiment of the presentinvention will be described with reference to FIG. 1. The apparatusshown in FIG. 1 serves to fabricate an EL display device which includesan EL element employing a transparent electrically-conductive film as ananode, a high-molecular EL layer as a light emitting layer, and a metalfilm as a cathode. The metal film containing an element that belongs tothe group-1 or group-2 of a periodic table.

Referring to FIG. 1, numeral 101 designates a transport chamber into orout of which a substrate is taken, and which is also called a “load lockchamber”. A carrier 102 on which the substrate is set is arranged here.Incidentally, the transport chamber 101 may well be separated for takingthe substrate inwards and for taking the substrate outwards.

In addition, numeral 103 designates a common chamber which includes amechanism (“transport mechanism”) 105 for transporting the substrate104. A robot arm or the like for handling the substrate 104 is oneexample of the transport mechanism 105.

Besides, a plurality of processing chambers (indicated at numerals107˜111) are respectively connected to the common chamber 103 throughgates 106 a-106 f. In the construction shown in FIG. 1, the interior ofthe common chamber 103 is in a normal-pressure atmosphere which isfilled up with an inert gas (preferably, nitrogen gas, helium gas, neongas or argon gas). Since, however, the respective chambers 101, 107-111can be completely cut off from the common chamber 103 by thecorresponding gates 106 a˜106 f, gastight closed spaces can be defined.

It is accordingly permitted to perform processing in vacuum by disposinga vacuum pump for each chamber. Usable as the vacuum pump is a rotaryoil pump, a mechanical booster pump, a molecular turbopump or acryopump, among which the cryopump effective for eliminating moisture isespecially favorable.

The processing chamber indicated at numeral 107 serves to perform anoxidation process for bettering the surface of the transparentelectrically-conductive film formed on the substrate (hereinbelow, theprocessing chamber 107 shall be termed the “processing chamber foroxidation”). Here, preprocessing is executed for matching the junctionsurface potential of the transparent conductive film with the surfacepotential of the high-molecular EL layer. Techniques for thepreprocessing are the following three:

(1) Surface oxidation process which is based on an oxygen plasmautilizing a parallel-plate glow discharge.

(2) Surface oxidation process which is based on ozone produced byirradiation with ultraviolet light.

(3) Surface oxidation process which is based on oxygen radicals producedby a plasma.

Although the thin-film forming apparatus according to the presentinvention may well be furnished with the processing chamber forperforming any of the three surface oxidation processes, the methodwherein the ozone is produced by the ultraviolet light irradiation so asto implement the surface oxidation of the transparent conductive film issimple and favorable. Moreover, organic substances on and in the surfaceof the transparent conductive film are eliminated by the surfaceoxidation based on the ozone. Further, it is effective to satisfactorilyeliminate moisture by simultaneously heating the substrate on thisoccasion.

By the way, in evacuating the processing chamber for oxidation, 107,this chamber may be completely cut off from the common chamber 103 bythe gate 106b so as to implement the evacuation in a gastight state.

Next, the processing chamber indicated at numeral 108 serves to apply asolution containing the high-molecular EL material by the spin coatingprocess (hereinbelow, the processing chamber 108 shall be termed the“processing chamber for solution application”). Since, as explainedbefore, the EL material is very weak against moisture, the interior ofthe processing chamber for solution application, 108 needs to be alwaysheld in an inert atmosphere.

In this case; the gate 106 c also plays the role of a shutter whichprevents the organic solution from scattering. In bringing the interiorof the processing chamber 108 into a lowered-pressure state, thischamber may be completely cut off from the common chamber 103 by thegate 106 c.

Next, the processing chamber indicated at numeral 109 serves to bake athin coating film formed in the processing chamber for solutionapplication, 108 (hereinbelow, the processing chamber 109 shall betermed the “processing chamber for baking”). Here, the thin film isheat-treated, thereby to remove the excessive part of the organicsolution and to perform a process for forming the high-molecular ELlayer. Insofar as the atmosphere of the baking process is an inert gas,it may be under the normal pressure. Since, however, the organic solventvolatilizes, the baking process should preferably be implemented invacuum. In that case, the processing chamber 109 may be cut off from thecommon chamber 103 by the gate 106 d.

Next, the processing chamber indicated at numeral 110 serves to form theelectrode by a vapor-phase film formation process (hereinbelow, theprocessing chamber 110 shall be termed the “processing chamber for firstvapor-phase film formation”). Vacuum evaporation or sputtering ismentioned as the vapor-phase film formation process. Here, the processis used for the purpose of forming the cathode on the high-molecular ELlayer, and hence, the vacuum evaporation being less prone to inflictdamages is more preferable. In either case, the processing chamber 110is cut off from the common chamber 103 by the gate 106 e, and the filmformation is implemented in vacuum.

By the way, with the thin-film forming apparatus shown in FIG. 1, thecathode is formed in the processing chamber for first vapor-phase filmformation, 110. Any known material may be employed as the material ofthe cathode. In addition, that surface of the substrate 104 which issubjected to the vacuum evaporation (that side of the substrate 104which is formed with the high-molecular EL layer) may conform to eitherof a face-up scheme and a face-down scheme.

The face-up scheme is very simple for the reason that the substrate 104transported from the common chamber 103 may be directly set on asusceptor. With the face-down scheme, the transport mechanism 105 or theprocessing chamber for first vapor-phase film formation, 110 needs to bepreviously furnished with a mechanism for turning the substrate 104inside out, so that the transport becomes complicated. This face-downscheme, however, attains the advantage that contaminants adhere little.

By the way, in the case where the vacuum evaporation process isperformed in the processing chamber for first vapor-phase filmformation, 110, an evaporation source needs to be included beforehand.In this regard, a plurality of evaporation sources may well be mounted.Besides, the evaporation source or sources may conform to either of aresistance heating type and an EB (electron beam) type.

Next, the processing chamber indicated at numeral 111 serves to form anelectrode by a vapor-phase film formation process (hereinbelow, theprocessing chamber 111 shall be termed the “processing chamber forsecond vapor-phase film formation”). Here, the electrode to be formed isan auxiliary electrode which assists the cathode. In addition, vacuumevaporation or sputtering can be employed, and the former is morepreferable because of being less prone to inflict damages. In eithercase, the processing chamber 111 is cut off from the common chamber 103by the gate 106 f, and the film formation is implemented in vacuum.

Besides, in the case where the vacuum evaporation is performed as thevapor-phase film formation process, an evaporation source needs to bemounted. The evaporation source may be the same as that of theprocessing chamber for first vapor-phase film formation, 110, and shalltherefore been omitted from description here.

The metal film which is often employed as the cathode, is one whichcontains the element belonging to the group-1 or group-2 of the periodictable. Since such a metal film is liable to oxidize, the surface thereofshould desirably be protected beforehand. Besides, since the requiredthickness of the metal film is small, an electrically conductive film oflow resistivity (the auxiliary electrode mentioned above) is provided asan auxiliary, thereby to lower the resistance of the cathode.Simultaneously, the protection of the cathode is attained by theconductive film of low resistivity. A metal film whose main component isaluminum, copper or silver is employed as the auxiliary conductive film.

Incidentally, the above processing steps (evacuation, transport, filmformation process, etc.) can be performed by a computerized fullyautomatic control which is based on a touch panel and a sequencer.

The most important features of the thin-film forming apparatusconstructed as described above, consist in that the formation of the ELlayer is done by the spin coating process, and that the means thereforis installed in the thin-film forming apparatus of multi-chamber system,together with the means for forming the cathode. Accordingly, theprocessing steps which begin with the step of oxidizing the surface ofthe anode made of the transparent conductive film and which end in thestep of forming the auxiliary electrode, can be performed withoutexposing the substrate structure to the open air anytime.

As a result, it is permitted to form the high-molecular EL layer immuneagainst degradation, by the simple means, and to fabricate the ELdisplay device of high reliability.

Embodiment 2

In this embodiment, an example in which the thin-film forming apparatusshown in FIG. 1 is partially altered will be described with reference toFIG. 2. Concretely, this embodiment is so constructed that a processingchamber for evacuation, 201 is interposed between the common chamber 103and the processing chamber for solution application, 108. Incidentally,regarding description on the parts other than the altered point,Embodiment 1 can be cited.

Although Embodiment 1 has mentioned the example in which the commonchamber 103 is filled up with the inert gas so as to have its interiorkept under the normal pressure, the substrate 104 may well betransported in vacuum. In this case, the pressure of the interior of thecommon chamber 103 may be lowered to several mTorr through several tensmTorr. On this occasion, the processing chamber for solutionapplication, 108 is filled up with the inert gas so as to have itsinterior kept under the normal pressure. Accordingly, the differencebetween the internal pressures of the chambers 103 and 108 must beovercome.

In this embodiment, therefore, the pressure of the processing chamberfor evacuation, 201 is first lowered to that of the common chamber 103,and the gate 106 d is opened in the lowered-pressure state so as totransport the substrate 104 into the processing chamber 201. After thegate 106 d has been shut, the interior of the processing chamber forevacuation, 201 is purged with an inert gas. When the internal pressureof the chamber 201 has recovered the normal pressure, a gate 202 isopened so as to transport the substrate 104 into the processing chamberfor solution application, 108. The transport here may be done stage bystage, or may well be done with dedicated transport means.

Further, when the step of solution application has ended, the gate 202is opened so as to transport the substrate 104 into the processingchamber for evacuation, 201, and this chamber 201 is evacuated in astate where the gate 202 and the gate 106 d are shut. When the interiorof the processing chamber for evacuation, 201 has reached thelowered-pressure state of the common chamber 103 in due course, the gate106 d is opened so as to transport the substrate 104 into the commonchamber 103.

Incidentally, although the processing chamber for baking, 109 isdisposed in this embodiment, the susceptor of the processing chamber forevacuation, 201 may well be made heatable so as to perform the step ofbaking here. Degassing can be suppressed by evacuating the processingchamber 201 after the baking.

Owing to the construction as described above, it is permitted to handlethe substrate 104 in vacuum in all the chambers except the processingchamber for solution application, 108. If the interior of the commonchamber 103 is in the lowered-pressure state, a time period in which adesired internal pressure is reached can be shortened in evacuating theprocessing chamber for surface oxidation, 107, the processing chamberfor baking, 109, the processing chamber for first vapor-phase filmformation, 110 or the processing chamber for second vapor-phase filmformation, 111, so that the throughput of the thin-film formingapparatus can be enhanced.

Embodiment 3

In this embodiment, an example in which the thin-film forming apparatusshown in FIG. 1 is partially altered will be described with reference toFIG. 3. Concretely, this embodiment is so constructed that the transportchamber 101 is furnished with a glove box 301 and a pass box 302.Incidentally, regarding description on the parts other than the alteredpoint, Embodiment 1 can be cited.

The glove box 301 is connected to the transport chamber 101 through agate 303. Processing for finally enveloping the EL element in a sealedspace, is performed in the glove box 301. This processing is one inwhich the substrate 104 subjected to all the processing steps (thesubstrate 104 having returned to the transport chamber 101 after theprocessing steps in the thin-film forming apparatus shown in FIG. 3) isprotected from the open air, and which employs such an expedient asmechanically enveloping the substrate 104 with a sealing material (alsotermed “housing material”) or enveloping it with a thermosetting resinor a ultraviolet-setting resin.

Usable as the sealing material is any of materials such as glass,ceramics and metals. In a case where light is caused to emerge onto theside of the sealing material, this material must be light-transmissible.Besides, the sealing material and the substrate 104 subjected to all theprocessing steps are stuck together with the thermosetting resin or theultraviolet-setting resin, and the resin is set by a heat treatment or atreatment of irradiation with ultraviolet light, thereby to define thesealed space. It is also effective that a drying agent such as bariumoxide is put in the sealed space.

Alternatively, the EL element can be enveloped by only the thermosettingresin or the ultraviolet-setting resin without employing the sealingmaterial. In this case, the thermosetting resin or theultraviolet-setting resin may be applied and set so as to cover, atleast, the side surfaces of the substrate 104 subjected to all theprocessing steps. This contrivance serves to prevent moisture fromintruding from film interfaces.

With the construction of the thin-film forming apparatus shown in FIG.3, a mechanism for the irradiation with ultraviolet light (hereinbelow,termed the “ultraviolet irradiation mechanism”), 304 is mounted insidethe glove box 301. The ultraviolet-setting resin is set by theultraviolet light emitted from the ultraviolet irradiation mechanism304.

Incidentally, although operations in the glove box 301 may well bemanual, a structure in which the operations are mechanically executedunder a computer control is favorable. In the case of employing thesealing material, it is favorable to incorporate a mechanism forapplying a sealant (here, the thermosetting resin or theultraviolet-setting resin) as is employed at the step of assembling thecell of a liquid crystal, a mechanism for sticking substrates together,and a mechanism for setting the sealant.

Besides, the interior of the glove box 301 can have its pressure loweredby attaching a vacuum pump. In a case where the step of envelopment ismechanically performed by robot motions, it is effectively done underthe lowered pressure.

Next, the pass box 302 is connected to the glove box 301 through a gate305. The pass box 302 can also have its internal pressure lowered byattaching a vacuum pump. This pass box 302 is an equipment which servesto prevent the interior of the glove box 301 from being directly exposedto the open air, and out of which the substrate 104 is taken.

As described above, with the thin-film forming apparatus of thisembodiment, the substrate 104 is exposed to the open air at the stage atwhich the EL element has been completely enveloped in the sealed space.Therefore, the EL element can be substantially perfectly prevented fromdegrading due to moisture etc. That is, it is permitted to fabricate theEL display device of high reliability.

Incidentally, it is possible to add the feature of Embodiment 2 (theprocessing chamber for evacuation, 201 shown in FIG. 2) to the thin-filmforming apparatus shown in FIG. 3. Thus, it is permitted to enhance thereliability of the EL display device still more.

Embodiment 4

In this embodiment, a case where the present invention is applied to athin-film forming apparatus of in-line system will be described withreference to FIG. 4. By the way, this apparatus corresponds basically toa case where the thin-film forming apparatus of multi-chamber system asshown in FIG. 1 has been altered to the in-line system, so thatEmbodiment 1 may be cited regarding description on individual processingchambers.

Referring to FIG. 4, numeral 401 designates a first transport chamberinto which a substrate is taken, and which is provided with a carrier402. The first transport chamber 401 is connected to a first commonchamber 404 through a gate 403. The first common chamber 404 isfurnished with a first transport mechanism 405. In addition, aprocessing chamber for oxidation, 407 is connected to the first commonchamber 404 through a gate 406, and a processing chamber for solutionapplication, 409 is connected thereto through a gate 408.

The substrate processed in the processing chamber for oxidation, 407 andthe processing chamber for solution application, 409 in the ordermentioned, is taken into a second transport chamber 411 which isconnected to the first common chamber 404 through a gate 410. A secondcommon chamber 413 is connected to the second transport chamber 411through a gate 412. The second common chamber 413 is furnished with asecond transport mechanism 414, by which the substrate is taken out ofthe second transport 411.

Besides, a processing chamber for baking, 416 is connected to the secondcommon chamber 413 through a gate 415, and a processing chamber forfirst vapor-phase film formation, 418 is connected thereto through agate 417. Further, the substrate processed in the processing chamber forbaking, 416 and the processing chamber for first vapor-phase filmformation, 418 in the order mentioned, is taken into a third transportchamber 420 which is connected to the second common chamber 413 througha gate 419.

A third common chamber 422 is connected to the third transport chamber420 through a gate 421. The third common chamber 422 is furnished with athird transport mechanism 423, by which the substrate is taken out ofthe third transport chamber 420. Besides, a processing chamber forsecond vapor-phase film formation, 425 is connected to the third commonchamber 422 through a gate 424, and a fourth transport chamber 427 fortaking out the substrate is connected thereto through a gate 426. Thefourth transport chamber 427 is provided with a carrier 428.

As described above, this embodiment consists in the in-lined thin-filmforming apparatus in which the plurality of processing chambers areconnected to realize a through process.

By the way, a processing chamber for evacuation may well be interposedbetween the processing chamber for solution application, 409 and thefirst common chamber 404 in the same manner as in Embodiment 2. Alsoallowed is a construction in which, in the same manner as in Embodiment3, a glove box and a pass box are connected to the fourth transportchamber 427, so as to take out the substrate after the envelopment ofthe EL element.

Embodiment 5

Embodiments 1-4 have exemplified the construction in which theprocessing chamber for oxidation, the processing chamber for solutionapplication, the processing chamber for baking, the processing chamberfor first vapor-phase film formation and the processing chamber forsecond vapor-phase film formation are disposed as the plurality ofprocessing chambers. The present invention, however, is not restrictedto such a combination.

If necessary, it is also allowed to dispose two or more processingchambers for solution application, or three or more processing chambersfor vapor-phase film formation. Besides, the processing chamber forvapor-phase film formation may well be used for the formation of alow-molecular EL layer, apart from the formation of the metal film. Itis also possible, for example, to form a light emitting layer by spincoating and then stack an electron transporting layer thereon by vacuumevaporation, or to form a hole transporting layer by spin coating andthen stack a light emitting layer thereon by vacuum evaporation. Ofcourse, a low-molecular EL layer formed by vacuum evaporation may wellbe overlaid with a high-molecular EL layer by spin coating.

It is also effective that an insulating film, preferably an insulatingfilm containing silicon, is formed covering the EL element as a finalpassivation film. In that case, the insulating film may be formed bysputtering or vacuum evaporation in the processing chamber forvapor-phase film formation. Incidentally, a silicon nitride film or asilicon nitride oxide film whose oxygen content is low is favorable asthe insulating film containing silicon.

As described above, the present invention is not restricted to thecombination of the plurality of processing chambers, but the functionsof processing chambers to be disposed may be properly determined by aperson in charge. Incidentally, Embodiment 1 can be cited regardingdescription on the individual processing chambers.

Embodiment 6

In this embodiment, an example in which the thin-film forming apparatusof the present invention is adopted in fabricating an EL display deviceof active matrix type will be described with reference to FIGS. 5(A)through 5(D). By the way, in this embodiment, the apparatus described inEmbodiment 1 will be taken as an example. Accordingly, the descriptionof Embodiment 1 can be cited regarding the details of the processingsteps which are performed in the individual processing chambers.

First, as shown in FIG. 5(A), pixels 502 arrayed in the shape of amatrix are formed on a glass substrate 501. Although the glass substrate501 is employed in this embodiment, any material may be used for asubstrate. However, in a case where light is emitted from an EL elementonto a substrate side as in this embodiment, the substrate must belight-transmissible.

Besides, each of the pixels 502 has a TFT 503 and a pixel electrode(anode) 504, and a current to flow to the pixel electrode 504 iscontrolled by the TFT 503. A method of fabricating the TFTs 503 mayconform to any known method of fabricating TFTs. Of course, the TFT 503may be either a top gate type TFT or a bottom gate type TFT. (FIG. 5(A))

Further, the pixel electrode 503 is formed using a transparentelectrically-conductive film such as of a compound comprising indiumoxide and tin oxide (and which is called “ITO”), or a compoundcomprising indium oxide and zinc oxide. In this embodiment, a compoundin which 10-15% of zinc oxide is mixed in indium oxide is employed.

Subsequently, the substrate shown in FIG. 5(A) is put in the carrier102, and this carrier 102 is set in the transport chamber 101 of thethin-film forming apparatus shown in FIG. 1. Besides, the substrate istransported by the transport mechanism 105 into the processing chamberfor oxidation, 107, in which the surfaces of the anodes 504 arebettered. In this embodiment, in a state where oxygen gas is introducedinto the evacuated processing chamber 107, ultraviolet light isprojected, and the substrate is exposed in an ozone atmosphere thuscreated, thereby to better the surface potentials of the pixelelectrodes 504.

Subsequently, the substrate is transported into the processing chamberfor solution application, 108 by the transport mechanism 105, and it iscoated with a solution containing an EL material, by spin coating,thereby to form the preform 505 of a high-molecular EL layer. In thisembodiment, a solution in which polyvinyl carbazole is dissolved inchloroform is employed. Of course, any other appropriate combinationbetween a high-molecular EL material and an organic solvent may well beemployed. (FIG. 5(B))

Further, the resulting substrate is transported into the processingchamber for baking, 109, in which a baking process (a heat treatment) isperformed to polymerize the EL material. In this embodiment, the wholesubstrate is heat-treated at a temperature of 50-150° C. (morepreferably, 110-120° C.) by heating a stage by means of a heater. Thus,excessive chloroform is volatilized to form the high-molecular EL layer(a polyvinyl carbazole film) 506. (FIG. 5(C))

When the state of FIG. 5(C) has been obtained, the substrate istransported into the processing chamber for first vapor-phase filmformation, 110, in which a cathode 507 made of a metal film thatcontains an element belonging to the group-1 or group-2 of a periodictable is formed by vacuum evaporation. In this embodiment, magnesium andsilver are co-evaporated at a rate of 10:1, thereby to form the cathode507 made of an Mg—Ag alloy.

Further, the substrate formed with the cathode 507 is taken out of theprocessing chamber for first vapor-phase film formation, 110 and intothe processing chamber for second vapor-phase film formation, 111 by thetransport mechanism 105. In the latter processing chamber 111, anelectrode (auxiliary electrode) 508 whose main component is aluminum isformed on the cathode 507. Thus, the state of FIG. 5(D) is obtained.

Thereafter, a passivation film such as a silicon nitride film may wellbe provided by vacuum evaporation or sputtering at need. In the case ofproviding the passivation film, the thin-film forming apparatus may bepreviously equipped with a processing chamber for forming an insulatingfilm, or the substrate may be taken out once and formed with thepassivation film by another apparatus.

Besides, using the thin-film forming apparatus as shown in Embodiment 3,the EL element may well be finally enveloped before the substrate isexposed to the open air.

Incidentally, although this embodiment has exemplified the applicationof the thin-film forming apparatus of the present invention to thefabrication of the active matrix type EL display device, the apparatusis also applicable to the fabrication of a simple matrix type EL displaydevice. Besides, the thin-film forming apparatus in any of Embodiments2-5 may well be applied.

Embodiment 7

In this embodiment, another example in which the thin-film formingapparatus of the present invention is adopted in fabricating an ELdisplay device of active matrix type will be described with reference toFIGS. 6(A) through 6(E). By the way, in this embodiment, the apparatusdescribed in Embodiment 1 will be taken as an example. Accordingly, thedescription of Embodiment 1 can be cited regarding the details of theprocessing steps which are performed in the individual processingchambers.

First, as shown in FIG. 6(A), pixels 602 arrayed in the shape of amatrix are formed on a glass substrate 601. Although the glass substrate601 is employed in this embodiment, any material may be used for asubstrate.

Besides, each of the pixels 602 has a TFT 603 and a pixel electrode(cathode) 604, and a current to flow to the pixel electrode 604 iscontrolled by the TFT 603. A method of fabricating the TFTs 603 mayconform to any known method of fabricating TFTs. Of course, the TFT 603may be either a top gate type TFT or a bottom gate type TFT. (FIG. 6(A))Further, the pixel electrode 603 may be formed of a film whose maincomponent is aluminum. In this embodiment, light emitted from an ELelement is caused to emerge onto the side opposite to the substrate 601(upwards as viewed in FIG. 6(A)). On this occasion, the pixel electrode603 functions as a reflecting electrode. It is therefore favorable toemploy a material which exhibits the highest possible reflectivity.

Subsequently, the substrate shown in FIG. 6(A) is put in the carrier102, and this carrier 102 is set in the transport chamber 101 of thethin-film forming apparatus shown in FIG. 1. Besides, the substrate istransported by the transport mechanism 105 into the processing chamberfor first vapor-phase film formation, 110, in which cathodes 605 eachbeing made of a metal film that contains an element belonging to thegroup-1 or group-2 of a periodic table is formed by vacuum evaporation.In this embodiment, the cathodes 605 made of an Mg—Ag alloy are formed.Incidentally, the cathodes 605 are selectively formed in correspondencewith the respective pixel electrodes 604 by the vacuum evaporation whichemploys a mask. (FIG. 6(B)) Subsequently, the substrate is transportedinto the processing chamber for solution application, 108 by thetransport mechanism 105, and it is coated with a solution containing anEL material, by spin coating, thereby to form the preform 606 of ahigh-molecular EL layer. In this embodiment, a solution in whichpolyphenylene vinylene is dissolved in dichloromethane is employed. Ofcourse, any other appropriate combination between a high-molecular ELmaterial and an organic solvent may well be employed. (FIG. 6(C))Further, the resulting substrate is transported into the processingchamber for baking, 109, in which a baking process (a heat treatment) isperformed to polymerize the EL material. In this embodiment, the wholesubstrate is heat-treated at a temperature of 50-150° C. (morepreferably, 110-120° C.) by heating a stage by means of a heater. Thus,excessive dichloromethane is volatilized to form the high-molecular ELlayer (a polyphenylene vinylene film) 607. (FIG. 6(D))

When the state of FIG. 6(D) has been obtained, the substrate istransported into the processing chamber for second vapor-phase filmformation, 111, in which an anode 608 made of a transparent conductivefilm is formed by sputtering. In this embodiment, a compound in which10-15% of zinc oxide is mixed in indium oxide is employed. Thus, thestate of FIG. 6(E) is obtained.

Thereafter, a passivation film such as a silicon nitride film may wellbe provided by vacuum evaporation or sputtering at need. In the case ofproviding the passivation film, the thin-film forming apparatus may bepreviously equipped with a processing chamber for forming an insulatingfilm, or the substrate may be taken out once and formed with thepassivation film by another apparatus.

Besides, using the thin-film forming apparatus as shown in Embodiment 3,the EL element may well be finally enveloped before the substrate isexposed to the open air.

Incidentally, although this embodiment has exemplified the applicationof the thin-film forming apparatus of the present invention to thefabrication of the active matrix type EL display device, the apparatusis also applicable to the fabrication of a simple matrix type EL displaydevice. Besides, the thin-film forming apparatus in any of Embodiments2-5 may well be applied.

The present invention brings forth effects as stated below.

A processing chamber for forming the layer of a high-molecular ELmaterial by a spin coating process, and other processing chambers forpreprocessing and for forming electrodes are integrated in conformitywith a multi-chamber system or an in-line system, whereby an EL elementemploying the high-molecular EL material can be fabricated without theproblem of degradation. It is accordingly possible to sharply enhancethe reliability of an EL display device employing the high-molecular ELmaterial.

1. An apparatus comprising: at least first and second common chambers; atransport chamber provided between the first common chamber and thesecond common chamber; a first vapor-phase film formation chamberconnected to the first common chamber with a first gate interposedtherebetween; and a second vapor-phase film formation chamber connectedto the second common chamber with a second gate interposed therebetween,wherein a means for transporting is provided in each of the first andsecond common chambers.
 2. An apparatus comprising: at least first andsecond common chambers; a transport chamber provided between the firstcommon chamber and the second common chamber; a chamber for sputteringconnected to the first common chamber with a first gate interposedtherebetween; and a chamber for vapor deposition connected to the secondcommon chamber with a second gate interposed therebetween, wherein ameans for transporting is provided in each of the first and secondcommon chambers.
 3. An apparatus comprising: at least first and secondcommon chambers; a transport chamber provided between the first commonchamber and the second common chamber; a first vapor-phase filmformation chamber connected to the first common chamber with a firstgate interposed therebetween; a second vapor-phase film formationchamber connected to the second common chamber with a second gateinterposed therebetween; and a means for enveloping an EL element in asealed space, connected to the first common chamber with at least athird gate interposed therebetween, and wherein a means for transportingis provided in each of the first and second common chambers.
 4. Anapparatus comprising: first, second, and third common chambers; a firsttransport chamber provided between the first common chamber and thesecond common chamber; a second transport chamber provided between thesecond common chamber and the third common chamber; a first vapor-phasefilm formation chamber connected to the first common chamber with afirst gate interposed therebetween; and a second vapor-phase filmformation chamber connected to the second common chamber with a secondgate interposed therebetween, wherein a means for transporting isprovided in each of the first and second common chambers.
 5. Anapparatus comprising: first, second, and third common chambers; a firsttransport chamber provided between the first common chamber and thesecond common chamber; a second transport chamber provided between thesecond common chamber and the third common chamber; a first vapor-phasefilm formation chamber connected to the first common chamber with afirst gate interposed therebetween; and a second vapor-phase filmformation chamber connected to the second common chamber with a secondgate interposed therebetween, a means for enveloping an EL element in asealed space, connected to the first common chamber with at least athird gate interposed therebetween, and wherein a means for transportingis provided in each of the first and second common chambers.
 6. Anapparatus comprising: first, second, and third common chambers; a firsttransport chamber provided between the first common chamber and thesecond common chamber; a second transport chamber provided between thesecond common chamber and the third common chamber; a first vapor-phasefilm formation chamber connected to the first common chamber with afirst gate interposed therebetween; a second vapor-phase film formationchamber connected to the second common chamber with a second gateinterposed therebetween; and a processing chamber for evacuationconnected to the third common chamber with at least a third gateinterposed therebetween, wherein a means for transporting is provided ineach of the first and second common chambers.
 7. An apparatus accordingto claim 4, wherein a processing chamber for solution application isconnected to the third common chamber with a fourth gate interposedtherebetween.
 8. An apparatus according to claim 5, wherein a processingchamber for solution application is connected to the third commonchamber with a fourth gate interposed therebetween.
 9. An apparatusaccording to claim 6, wherein a processing chamber for solutionapplication is connected to the third common chamber with a fourth gateinterposed therebetween.
 10. An apparatus according to claim 4, whereina processing chamber for oxidation is connected to the third commonchamber with a fourth gate interposed therebetween.
 11. An apparatusaccording to claim 5, wherein a processing chamber for oxidation isconnected to the third common chamber with a fourth gate interposedtherebetween.
 12. An apparatus according to claim 6, wherein aprocessing chamber for oxidation is connected to the third commonchamber with a fourth gate interposed therebetween.
 13. An apparatusaccording to claim 1, wherein a processing chamber for baking isconnected to the second common chamber with a fourth gate interposedtherebetween.
 14. An apparatus according to claim 2, wherein aprocessing chamber for baking is connected to the second common chamberwith a fourth gate interposed therebetween.
 15. An apparatus accordingto claim 3, wherein a processing chamber for baking is connected to thesecond common chamber with a fourth gate interposed therebetween.
 16. Anapparatus according to claim 4, wherein a processing chamber for bakingis connected to the second common chamber with a fourth gate interposedtherebetween.
 17. An apparatus according to claim 5, wherein aprocessing chamber for baking is connected to the second common chamberwith a fourth gate interposed therebetween.
 18. An apparatus accordingto claim 6, wherein a processing chamber for baking is connected to thesecond common chamber with a fourth gate interposed therebetween.